Kidney cancer is malignancy of the kidney, the organ
that is primarily responsible for the removal of metabolic products from the
body. The types of kidney cancer in adults and children are different and distinct:
In adults kidney cancer tends to occur after age 50 and strikes men twice as
often as women. The most common type occurs in the renal (kidney) tissue that
filters the blood and produces the urine and is called renal cell cancer
(or renal cell carcinoma). Another type of adult kidney tumor arises
in the renal pelvis where the urine collects and is called transitional cell
carcinoma. The most frequent diagnostic sign of kidney cancer in adults
is blood in the urine. In children the main type of kidney cancer
is Wilms’ tumor. It starts to develop in fetal life and may
be large by the time it is detected (on average at 3 years of age). Wilms’
tumor is associated with certain congenital defects including urinary tract
abnormalities, absence of the iris (aniridia) and hemihypertrophy
(enlargement of one side of the body), and shows an increased incidence among
siblings and twins. The tumor tends to cause a noticeable mass and sometimes
pain in the abdomen. Blood in the urine (hematuria) occurs in a minority
of cases.